1/20+1/30+1/42+1/56+1/72+1/90

来源：学生作业帮编辑：神马作文网作业帮分类：数学作业时间：2024/11/11 20:34:03

1/20+1/30+1/42+1/56+1/72+1/90
=1/4*5+1/5*6+1/6*7+1/7*8+1/8*9+1/9*10
=1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10
=1/4-1/10
=3/20

1/30+1/42+1/56+1/72+1/90 1/12+1/20+1/30+1/42+1/56+1/72+1/90=? 1/12+1/20+1/30+1/42+1/56+1/72+1/90 20/1+30/1+42/1+56/1+72/1+90/1 用简便方法计算. 1/20+1/30+1/42+1/56+1/72+1/90 20/1+30/1+42/1+56/1+72/1+90/1救简算算1/20+1/30+1/42+1/56+1/72+1/90 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+.1/9900 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/10 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110 谁能巧算1-1/2-1/6-1/12-1/20-1/30-1/42-1/56-1/72-1/90 1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110 急!